Delay line for travelling wave tubes



Nov. 17, 1964 F. GROSS 3,157,814

DELAY LINE FOR TRAVELLIKG WAVE TUBES Filed Dec. 12. 1960 Fig.1

[Sikh United States Patent DELAY LINE FOR TRAVELLING WAVE TUBES Franz Gross, Munich, Germany, assignor to Siemens &

Halske Aktiengesellschaft Berlin and Munich, a corporation of Germany Filed Dec. 12, 1960, Ser. No. 75,198 Claims priority, application Germany Apr. 11, 1960 Claims. (Cl. 315-35) This invention is concerned with a delay line for travelling wave tubes, employed for amplifying millimeter waves, consisting of a wave guide made in the form of a hollow conductor and comprising strip-shaped transverse webs which are alternately arranged at oppositely positioned wall portions and electrically connected therewith, such transverse webs extending into the space of reciprocal action between a wave propagated along the line and an electron beam extending through openings in the transverse Webs.

The object of the invention is to provide a delay line for the amplification of millimeter waves, which assures a wide band and stable amplifying operation with the forwardly propagated first partial wave.

There are already delay lines known for the production of electrical oscillations with a wave length in the order of magnitude from 1 centimeter to 1 meter, consisting of a hollow wave guide, strip-shaped webs disposed therein and extending transverse to the longitudinal direction thereof. These strip-shaped webs are spaced apart approximately uniformly and are arranged at oppositely positioned wall portions in electrical contact therewith.

These known delay lines are unsuitable for amplifica tion operation and are moreover not directly applicable for millimeter waves, since a reduction, for example, of the dimensions thereof would result in an appreciable decrease of the output of a tube equipped therewith.

The invention proposes the solution of the problem, to provide, in connection with the previously explained delay line, symmetrical to the transverse webs two longitudinal webs which extend from the inner wall of the Wave guide into direct proximity of the transverse webs.

The various objects and features of the invention will be explained below with reference to the accompanying drawing.

FIGS. 1 to 3 show thin metal sheet members which may be in simple manner stacked or assembled in proper sequence and interconnected, for example, by means of gold solder, to form a delay line of desired length;

FIGS. 4 to 6 show differently shaped thin metal sheet members for the same purpose;

FIGS. 7 to 9 represent further differently shaped metal sheet members forconstructing a delay line in the same manner;

FIG. 10 is a dispersion diagram, for the fundamental wave and the fowardly propagated first partial wave, of two delay lines constructed of metal sheet members respectively according to FIGS. 1-3, 4-6 and 7-9, and

FIG. 11 is a sectional elevation depicting a delay line conforming to the present invention.

Corresponding parts are identically referenced throughout the drawings.

The thin metal sheet members may be produced by stamping or by etching.

FIGS. 1, 2 and 3 show types of metal sheet members 1 and 2 which are to be stacked to form a delay line, the sheet member 1 being represented in FIG. 3 dis-. placed by 180 from the position in which it is shown in FIG. 1. The expression type of metal shee or similar language is intended to mean sheet members of identical form and size which are produced, for example, by means of identical stamping or punching tools. The sheet member 2 illustrates the cross sectional extent 3 of the wave 3,157,814 Patented Nov. 17, 1964 ice guide and defines the cross sectional extent of the longitudinal webs 4. The sheet member 1 represents the cross sectional extent 3 of the wave guide as well as the cross sectional extent of the longitudinal webs and of the transverse web 5. The transverse web 5 is provided with a hole 6 formed therein for the passage of the electron beam.

The metal sheets 7 and 8 indicated in FIGS. 4 to 6 diifer from the sheets 1 and 2 merely in that theydo not represent the cross sectional extent of .the' longitudinal webs. At the places at which the longitudinal webs merge in FIGS. 1-3 into the wave guide, there are provided rectangular grooves 9. After assembly of the sheet members 7 and 8 with the grooves or recesses 9 thereof in alignment, longitudinally extending Webs are soldered thereinto, the cross sectional extent of these webs being indicated in FIGS. 4-6 by dotted lines marked by reference numeral 10.

A particularly good coupling impedance may be obtained with a delay line constructed of metal sheet members 11 and 12 as shown in FIGS. 7-9. The longitudinal webs 4- are in the range of the transverse webs 5 provided with arcuate extensions 13, such extensions partially embracing the part of the respective transverse webs which have the holes 6 formed therein.

The curve 14 in FIG. 10 shows the dispersion curve of a delay line constructed respectively of metal sheets formed according to FIGS 1-3 and 4-6. The curve 15 shows the dispersion curve of a delay line constructed of metal sheets formed according to FIGS. 7-9. The ordinate indicates the amount of delay 0/ v. Upon the abscissa is plotted the wave length A in free space. References =1r and 1p=21r indicate border lines along which there is a phase displacement of and 360, between two adjacent transverse webs. The legs of the curves 14 and 15 extending between the abscissa and the straight line 1p=1r denotes the dispersion of the rearwardly propagated fundamental wave. The dispersion of the forwardly propagated first partial wave is represented by the leg of the curves 14 and 15 extending between the straight lines 1/ =1r and =21r.

A delay line with a dispersion according to curve 14 is adapted for very broad band amplification in the operating range of the forwardly propagated first partial wave. A delay line with a dispersion according to curve 15 is advantageous where band width requirements are less demanding, since it has a higher coupling impedance owing to lower group velocity.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

I claim:

1. A delay line for amplifying millimeter waves in connection with travelling wave tubes, comprising a plurality of sheet metal members of at least two different types defining a hollow wave guide comprising stripshaped transverse webs extending alternately from and electrically interconnected with oppositely positioned wall portions thereof, said transverse webs extending into the space of reciprocal action between a wave propagated along the line and an electron beam propagated through openings formed in the transverse webs, and means forming two longitudinally directed, substantially continuously extending webs arranged symmetrically with respect to the transverse Webs, said longitudinally directed webs extending from the inner wall of the wave guide into relatively close proximity with said transverse webs, wherein said sheet metal members include a first type which represents the cross sectional extent of the wave guide and the cross sectional extent of the transverse web, a second type which represents the cross sectional extent of the wave guide, and another of the first type adjacent 3 the second type and displaced by 180 relative tothe first said first type, said sheet metal members being stacked and mutually interconnected, assuring a wide band width and a stable amplifying operation with the fiwe td ptepa st P r al a 2. delay line according to claim 1, wherein both metal sheet types represent respectively the cross sectional extents of thefwave guide and that of the longitudinally re te w '3. 1ft delay line according to claim 1, wherein the longitudinally directed webs are soldered into longitudinally aligned recesses formed in both types of metal sheet members.

4. A delay line according to claim 2, wherein thelongitudinally directed webs are provided with arcuate extensions disposed in the range of the transverse webs.

5. A delay line according to claim 3, wherein the longitudinally directed webs are provided with arcuate extensions disposed in the range of the transverse webs.

References Cited in the file of this patent UNITED STATES PATENTS 2,806,973 McEwan et al. Sept. 17, 1957 2,827,589 Hines Mar. 18, 1958 2,858,472 Karp Oct. 28, 1958 2,926,280 Hergenrother Feb. 23, 1960 2,966,610 Schmidt et al. Dec. 27, 1960 3,011,085 Caldwell Nov. 28, 1 961 

1. A DELAY LINE FOR AMPLIFYING MILLIMETER WAVES IN CONNECTION WITH TRAVELLING WAVE TUBES, COMPRISING A PLURALITY OF SHEET METAL MEMBERS OF AT LEAST TWO DIFFERENT TYPES DEFINING A HOLLOW WAVE GUIDE COMPRISING STRIPSHAPED TRANSVERSE WEBS EXTENDING ALTERNATELY FROM AND ELECTRICALLY INTERCONNECTED WITH OPPOSITELY POSITIONED WALL PORTIONS THEREOF, SAID TRANSVERSE WEBS EXTENDING INTO THE SPACE OF RECIPROCAL ACTION BETWEEN A WAVE PROPAGATED ALONG THE LINE AND AN ELECTRON BEAM PROPAGATED THROUGH OPENINGS FORMED IN THE TRANSVERSE WEBS, AND MEANS FORMING TWO LONGITUDINALLY DIRECTED, SUBSTANTIALLY CONTINUOUSLY EXTENDING WEBS ARRANGED SYMMETRICALLY WITH RESPECT TO THE TRANSVERSE WEBS, SAID LONGITUDINALLY DIRECTED WEBS EXTENDING FROM THE INNER WALL OF THE WAVE GUIDE INTO RELATIVELY CLOSE PROXIMITY WITH SAID TRANSVERSE WEBS, WHEREIN SAID SHEET METAL MEMBERS INCLUDE A FIRST TYPE WHICH REPRESENTS THE CROSS SECTIONAL EXTENT OF THE WAVE GUIDE AND THE CROSS SECTIONAL EXTENT OF THE TRANSVERSE WEB, A SECOND TYPE WHICH REPRESENTS THE CROSS SECTIONAL EXTENT OF THE WAVE GUIDE, AND ANOTHER OF THE FIRST TYPE ADJACENT THE SECOND TYPE AND DISPLACE BY 180* RELATIVE TO THE FIRST SAID FIRST TYPE, SAID SHEET METAL MEMBERS BEING STACKED AND MUTUALLY INTERCONNECTED, ASSURING A WIDE BAND WIDTH AND A STABLE AMPLIFYING OPERATION WITH THE FORWARDLY PROPAGATED FIRST PARTIAL WAVE. 